The present invention relates to a laminate of a perfluororubber and a method for producing the same. In particular, the present invention relates to a laminate comprising a layer of a perfluororubber and a layer of other rubber, which are adhered by vulcanizing, and a method for producing the same.
Perfluororubbers are used in various fields which require chemical resistance, thermal properties (in particular, high temperature properties), etc., since they are excellent in such properties.
However, the perfluororubbers are generally expensive and have inferior mechanical properties (e.g. tensile strength, elongation at break, etc.) to general fluororubbers. Thus, it is preferable to use the perfluororubbers in the form of a laminate with other materials, but the perfluororubbers inherently have low adhesion properties with other materials. Furthermore, neither primers nor adhesives have been developed to adhere the perfluororubbers to other materials in good condition.
JP-A-64-54037 proposes the addition of an adhesion aid to other rubbers which are adhered to the perfluororubbers to improve the adhesion properties between them. However, in the case of a laminate comprising a layer of other rubber and a layer of a perfluororubber surrounding the layer of the other rubber, the adhesion aid compounded in the other rubber cannot diffuse outside of the laminate in the course of the secondary vulcanization. Rather, the adhesion aid accumulates at the interface between the layer of the other rubber and the layer of the perfluororubber, and interferes with the adhesion between the layers.
One object of the present invention is to provide a laminate comprising a layer of a perfluororubber and a layer of other material, in particular, other rubber, which are bonded with a high adhesion strength, irrespective of the shape of the laminate.
Another object of the present invention is to provide a method for producing such a laminate.
To achieve the above objects, the present invention provides a laminate comprising a layer of perfluororubber, a layer of other rubber and an adhesive layer containing a polyfunctional compound which adheres both rubber layers by vulcanization, and a method for producing a laminate comprising the steps of coating a polyfunctional compound on a surface of at least one of a layer of a perfluororubber and a layer of other rubber, laminating the layers with the coated surface facing the other layer, and vulcanizing the layers to adhere them.